Q.Which of the following is correct:

The correct statement is (c) — In prokaryotes, there are no membrane-bound organelles.

• Prokaryotic cells contain ribosomes but lack every membrane-bound organelle (such as ER, Golgi, mitochondria and a membrane-bound nucleus), so (c) is true.
• (a) is wrong: prokaryotic cells have no well-defined, membrane-bound nucleus, so not all cells possess a nucleus. …

Here you have to pick the single true statement, which means checking each option against what is known about prokaryotic and eukaryotic organisation.

(c) is correct. Prokaryotic cells are the simpler of the two great cell types. Apart from ribosomes, they contain none of the membrane-bound organelles found in eukaryotes — no endoplasmic reticulum, Golgi complex, lysosomes, mitochondria or plastids, and no membrane-bound nucleus. Their genetic material lies essentially naked in the cytoplasm.

Now the reasons the others are false:

• (a) "Cells of all living organisms have a nucleus." This is not true. Only eukaryotic cells have a proper, membrane-bound nucleus. Prokaryotic cells have no well-defined nucleus — their DNA is not enclosed in a nuclear membrane. Some mature eukaryotic cells, such as mammalian red blood cells and the sieve tube cells of plants, even lack a nucleus altogether. …

Method: Elimination by checking each option against one dividing principle

For a "which statement is correct" MCQ built from cell-biology facts, the fastest and safest way in is to identify the single organising idea the four options are quietly testing — here it's the prokaryote/eukaryote divide (nucleus, organelles) plus two more general biology truths (cell-wall distribution, origin of cells). Rather than trying to recall the "right" statement directly, work through all four options and actively disprove three of them; the one you cannot disprove is your answer. …